Digalactosyl Diglyceride Research Articles

Molecular interactions between phospholipids and glycolipids in a lipid bilayer

Molecular interactions between phospholipids and glycolipids in a lipid bilayer have been investigated in terms of permeability, micropolarity, microviscosity, particle size, and zeta potential. Glycolipids used are 1,2-diacyl [β- d-galactopyranosyl (1′-3)]-sn-glycerol (monogalactosyl diglyceride; MG) and 1,2-diacyl [α- d-galactopyranosyl (1′-6′) β- d-galactopyranosyl (1′-3)]-sn-glycerol (digalactosyl diglyceride;DG). Loposomal bilayer membrances are stabilized by the addition of suitable amounts of glycolipids, but higher amounts can destabilize the liposomes. Sugar chains in the glycolipids inhibit the permeability of glucose. Micropolarity is lowest for a 0.045 mole fraction of DG incorporated into the liposomes with cholesterol. The particle size is increased with an increase in the amount of glycolipids added. The absolute value of the zeta potential of the liposomes decreases on the addition of a glycolipid. An inhibiting effect of sugar chains on the aggregation of the liposomes is not found, because the sugar chains of MG and DG do not have sufficient chain lengths to inhibit the aggregation of the liposomes.

Purification and characterization of a new lipase from Fusarium sp. YM-30.

The extracellular lipase from Fusarium sp. YM-30 was purified by a procedure involving ultrafiltration, ammonium sulfate precipitation, and DEAE-Toyopearl 650M, CM-Toyopearl 650M, and Butyl-Toyopearl 650M column chromatographies. The purified lipase was homogeneous with 12kDa of molecular mass by SDS-PAGE, and had high specificities for mono- and diacylglycerols, but low toward triacylglycerols. The enzyme had maximum activity at pH 7.0 to 8.0 and 37 degrees C, and hydrolyzed digalactosyl diglyceride too.

Carbon-13 nuclear magnetic resonance spectroscopy of lipids: differential line broadening due to cross-correlation effects as a probe of membrane structure

We have obtained proton-coupled carbon-13 nuclear magnetic resonance (NMR) spectra of a variety of lipid-water and lipid-drug-water systems, at 11.7 T, as a function of temperature, using the "magic-angle" sample-spinning (MAS) NMR technique. The resulting spectra show a wide range of line shapes, due to interferences between dipole-dipole and dipole-chemical shielding anisotropy interactions. The differential line-broadening effects observed are particularly large for aromatic and olefinic (sp2) carbon atom sites. Coupled spectra of the tricyclic antidepressants desipramine and imipramine, in 1,2-dimyristoyl-sn-glycero-3-phosphocholine-water mesophases, show well-resolved doublets having different line shapes for each of the four aromatic methine groups, due to selective averaging of the four C-H dipolar interactions due to rapid motion about the director (or drug C2) axis. 2H NMR spectra of [2,4,6,8-2H4]desipramine (and imipramine) in the same 1,2-dimyristoyl-sn-glycero-3-phosphocholine-water mesophase exhibit quadrupole splittings of approximately 0-2 and approximately 20 kHz, indicating an approximate magic-angle orientation of the C2-2H(1H) and C8-2H(1H) vectors with respect to an axis of motional averaging, in accord with the 13C NMR results. Selective deuteration of imipramine confirms these ideas. Spectra of digalactosyl diglyceride [primarily 1,2-di[(9Z,12Z,15Z)-octadeca-9,12,15-trienoyl ]-3- (alpha-D-galactopyranosyl-1-6-beta-D-galactopyranosyl)-sn-glycerol]-H2O (in the L alpha phase) show a large differential line broadening for C9 but a reduced effect for C10, consistent with the results of 2H NMR of specifically 2H-labeled phospholipids [Seelig, J., & Waespe-Saracevic, N. (1978) Biochemistry 17, 3310-3315].(ABSTRACT TRUNCATED AT 250 WORDS)

Changes of Membrane Lipids in Apple Buds During Dormancy and Budbreak

The changes of membrane lipids in apple (Malus domestics Borkh. cv. Delicious) auxillary and terminal buds from August to April were determined. The predominant lipids were monogalactosyl diglyceride (MGDG), digalactosyl diglyceride (DGDG), phosphatidylcholine (PC), and phosphatidylethanolamine (PE). An increase in membrane polar lipids was associated with budbreak and bud growth from August to April. Linolenic acid was the predominant fatty acid in MGDG, DGDG, and PC, while linoleic acid was predominant in PE. Phosphatidylglycerol (PG) and phosphatidylinositol (PI) contained a high amount of palmitic acid. The ratio of (18:2 + 18:3) to 18:1 fatty acids in galactolipids in apple buds increased from August to April. ß-Sitosterol and sitosteryl ester were the predominant sterols in apple buds. An increase in sitosterol, a decrease in sitosteryl ester, and a decline in the ratio of free sterols to phospholipids occurred during budbreak in spring. A decrease in sitosterol was associated with bud expansion in spring.

Effect of Bavistin on lipid metabolism in groundnut ( Arachis hypogaea L.) leaves infected with peanut green mosaic virus (PGMV)

Quantitative changes in the amounts and the synthesis of glycolipids and phospholipids were examined in groundnut ( Arachis hypogaea L.) leaves in which symptoms of peanut green mosaic disease was suppressed by spraying with Bavistin (50% w w carbendazim). The levels of total lipids, and of individual glycolipids (monogalactosyl diglyceride, digalactosyl diglyceride and sulphoquinovosyl diglyceride) were considerably lower, and of individual phospholipids (phosphotidyl inositol, glycerol, choline, ethanolamine and diphosphotidyl glycerol) were marginally lower in virus-infected leaves than healthy leaves. The above lipids (except diphosphatidyl glycerol) were present in greater amounts in virus-infected leaves sprayed with Bavistin compared to unsprayed healthy and virus-infected samples, but the amounts were not as high as in sprayed, healthy samples. A similar trend was also observed with lipids of isolated chloroplasts. Time course experiments measuring incorporation of 14C-acetate indicated the decreased synthesis of the above lipids in isolated mesophyll cells of virus-infected leaves, and their increased synthesis in cells isolated from Bavistin treated plants. The results are interpreted to indicate the suppression of virus incited foliar symptoms and are analogously compared with the biochemical changes which occur during the greening of etiolated seedling leaves and in leaves with delayed senescence.

Seasonal Changes of Membrane Lipids in Apple Shoots

Composition changes in galactolipids, phospholipids, and sterols in apple shoots (Malus domestica Borkh. cv. Red Delicious) from August to April were determined. The predominant fatty acids in the membrane lipids of apple shoots were palmitic acid (C16:0), linoleic acid (C18:2), and linolenic acid (C18:3). The major galactolipid components in apple shoots were monogalactosyl diglyceride (MGDG) and digalactosyl diglyceride (DGDG). The amount of MGDG and DGDG increased from autumn to spring. Galactolipids contained highly unsaturated fatty adds, mainly linoleic (18:2) and linolenic (18:3) acid. The major individual phospholipids were phosphatidylcholine (PC) and phosphatidylethaeolamine (PE). β -Sitosterol and sitosteryl ester were the predominant sterols. The phloem contained higher amounts of galactolipids, phospholipids, and sterols than did the xylem tissue. There was a significant increase in the content of galactolipids and phospholipids and onsaturation of their fatty acids during cold acclimation. A decrease in the ratio of free sterols to phospholipids also occurred in apple shoots toward cold winter months. Composition changes in galactolipids, phospholipids, and sterols that were associated with growth cessation, defoliation and cold acclimation from fall to winter, were mostly reversed following deacclimation in spring.

In vitro incorporation of (I- 14C) acetate and (U- 14C) glucose into the lipids of buffalo bull spermatozoa

Buffalo bull spermatozoa (10 9 cells) on analysis yielded 2.5 mg lipids comprising 48.5% phospholipids, 30.6% neutral lipids and 20.9% glycolipids which were further fractionated into their various components. Buffalo spermatozoa preferred (I- 14C) acetate to (U- 14C) glucose for incorporation into various lipid species and the maximum incorporation occurred in neutral lipids followed by glycolipids and phospholipids. Among neutral lipids, mono- and diglycerides were actively labelled with (U- 14C) glucose as a substrate, and the cholesterol ester was the most actively labelled component when (I- 14C) acetate was used as substrate. Amongst the glycolipids, incorporation of (U- 14C) glucose was greatest into digalactosyl diglyceride, whereas (I- 14C) acetate incorporation was greatest into monogalactosyl diglyceride. Phosphatidyl serine and phosphatidyl glycerol were the most actively labelled phospholipids with (U- 14C) glucose as a substrate, and phosphatidyl inositol and phosphatidyl glycerol were the most actively labelled with (I- 14C) acetate as a substrate. The significance of the results in sperm capacitation is discussed.

Changes in membrane polar lipids associated with bud break in apple induced by nitroguanidines

The predominant lipids in membranes obtained from apple buds were galacto- and phospholipids. The major galactolipid components in apple bud were monogalactosyl diglyceride (MGDG) and digalactosyl diglyceride (DGDG). Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were the major phospholipids in the apple buds. α-Linolenic acid (C 18:3) was the major fatty acid in MGDG, DGDG, and PC. Phosphatidylglycerol (PG) is the only lipid to contain significant amounts of palmitic acid (C 16:0) in the dormant buds. An increase in the galacto- and phospholipids and the ratio of the unsaturated fatty acids to the corresponding saturated fatty acids of the buds occurred as a result of induction by 1-(3,5-dichlorophenyl)-3-nitroguanidine or 1-(α-ethylbenzyl)-3-nitroguanidine during bud break. The identities of fatty acids in apple buds were confirmed by gas chromatography-mass spectrometry.

Phosphorus nuclear magnetic resonance studies of lipid-protein interactions: human erythrocyte glycophorin and phospholipids.

Human erythrocyte glycophorin containing four molecules of phospholipid tightly bound to the protein was isolated from human red cell ghosts. This protein preparation was reconstituted into a digalactosyl diglyceride bilayer. The 31P NMR spectrum of this reconstituted membrane produced an axially symmetric powder pattern arising exclusively from the phospholipids bound to glycophorin. The width of the powder pattern, about 90 ppm, is about twice as broad as that normally exhibited by a phospholipid bilayer. The chemical shift tensor is perturbed relative to phospholipids in a bilayer. The spin-lattice relaxation rate of these protein-bound phospholipids is found to be nearly an order of magnitude faster than phospholipids in a bilayer. The results are consistent with phospholipids tightly bound to the membrane protein and undergoing rotational diffusion, perhaps as a complex of phospholipid and protein.

Modulation of dolichyl-phosphomannose synthase activity by changes in the lipid environment of the enzyme

Rat liver dolichyl-phosphomannose synthase (GDP mannose-dolicholphosphate mannosyltransferase; EC 2.4.1.83) was previously shown to catalyze optimal rates of mannosyl transfer to dolichyl-P when the polyprenol acceptor was incorporated into a phosphatidylethanolamine (PE) matrix that has a tendency to adopt a nonbilayer (hexagonal HII) phase [Jensen, J. W., & Schutzbach, J. S. (1985) Eur. J. Biochem. 153, 41-48]. The present investigations now further define the properties of the lipid environment that are essential for mannosyltransferase activity. Monogalactosyl diglyceride (MGDG), a glycoglycerolipid that prefers a nonbilayer-phase organization in isolation, was shown to provide a suitable lipid matrix for synthase activity. By comparison, the enzyme was not activated by digalactosyl diglyceride (DGDG), which forms stable bilayer structures upon hydration. Enzyme activity in MGDG/DGDG mixtures decreased as the proportion of DGDG in the dispersion was increased. Although bilayer-forming phospholipids supported low rates of mannosyl transfer, enzyme activity was stimulated by the addition of MGDG to either phosphatidylcholine (PC) or PE/PC (1:1) membranes. The incorporation of agents known to destabilize bilayer structures including dolichols, ubiquinone, dodecane, and cholesterol into PE/PC (1:1) membranes also increased the rate of mannosyl transfer. Enzyme activity in PC membranes was stimulated by the presence of gramicidin and also by greatly increased concentrations of the substrate, dolichyl-P. The results demonstrate that the enzyme does not have a requirement for PE and suggest that the physical state of the lipid matrix is an important determinant for reconstitution of the synthase and polyprenol phosphate substrate in a productive complex. The formation of an enzyme/lipid complex was demonstrated by sucrose density gradient centrifugation and could be correlated with the lipid requirements for enzyme activity.

Lipid requirement of the branched-chain amino acid transport system of Streptococcus cremoris.

The role of the membrane lipid composition on the transport protein of branched-chain amino acids of the homofermentative lactic acid bacterium Streptococcus cremoris has been investigated. The major membrane lipid species identified in S. cremoris were acidic phospholipids (phosphatidylglycerol and cardiolipin), glycolipids, and glycerophosphoglycolipids. Phosphatidylethanolamine (PE) was completely absent. Protonmotive force-driven and counterflow transport of leucine was assayed in fused membranes of S. cremoris membrane vesicles and liposomes composed of different lipids obtained by the freeze/thaw-sonication technique. High transport activities were observed with natural S. cremoris and Escherichia coli lipids, as well as with mixtures of phosphatidylcholine (PC) with PE or phosphatidylserine. High transport activities were also observed with mixtures of PC with monogalactosyl diglyceride, digalactosyl diglyceride, or a neutral glycolipid fraction isolated from S. cremoris. PC or mixtures of PC with phosphatidylglycerol, phosphatidic acid, or cardiolipin showed low activities. In mixtures of PC and methylated derivatives of PE, both counterflow and protonmotive force-driven transport activities decreased with increasing degree of methylation of PE. The decreased transport activity in membranes containing PC could be restored by refusion with PE-containing liposomes. These results demonstrate that both aminophospholipids and glycolipids can be activators of the leucine transport system from S. cremoris. It is proposed that aminophospholipids in Gram-negative bacteria and glycolipids in Gram-positive bacteria have similar functions with respect to solute transport.

Glycolipids in Oil Palm Leaf, Crude Palm Oil, Fiber, and Empty Bunch

Glycolipids were isolated from oil palm leaves, crude palm oil (CPO), fibers and an empty bunch, and were determined and purified by TLC. Glycolipids were identified in most cases by Rf values in TLC and coloring reactions. 1-Naphthol and perchloric acid were used to stain the glycolipids and steryl glycosides, respectively. The glycolipid composition was determined by both charring and staining followed by densitometry. Esterified steryl glycoside, monogalactosyl diglyceride, steryl glycoside (SG), cerebroside, digalactosyl diglyceride and sulfoquinovosyl diglyceride (SQDG) were the major glycolipids from the oil palm leaves, while, in CPO, SG and SQDG were not present. SQDG was also not present in the fibers or empty bunch.The fatty acid composition of each glycolipid in the oil palm leaves and CPO were also analyzed and compared for typical saturated and unsaturated fatty acid content. Among the saturated fatty acids, palmitic acid was found in both the oil palm leaves and CPO glycolipids. Among unsaturated fatty acids, linolenic acid was characteristic in the oil palm leaves, and oleic acid was present in CPO.

Stimulation by target cell membrane lipid of actin polymerization and phagocytosis by Entamoeba histolytica.

The identity of molecules of mammalian target cells that stimulate contact-dependent attack by Entamoeba histolytica was sought using human erythrocytes (RBC) as a model. Protein-free liposomes prepared from RBC membrane lipids stimulated the same rapid E. histolytica actin polymerization and phagocytosis as did whole target cells. Liposomes constructed from the major phospholipids of RBC stimulated these responses but only if a negatively charged phospholipid was included. The addition to these liposomes of digalactosyl diglyceride significantly enhanced their stimulatory activity. The results demonstrate that ligands that trigger attack-related responses by E. histolytica reside in the target cell membrane lipid fraction and suggest roles for both glycolipid and phospholipid components.

Supercritical fluid extraction and characterization of lipids from algae Scenedesmus obliquus.

Supercritical carbon dioxide (SC-CO2) extractions (with and without ethanol as an entrainer) were carried out to remove lipids and pigments from protein concentrate of green algae (Scenedesmus obliquus) cultivated under controlled conditions. The content and fatty acid composition of algal lipids using column, thin-layer (TLC) and gas-liquid chromatography (GLC) were determined. Absorption spectra of extracted fractions showed the predominance of chlorophyll A (lambda max at 410 nm). Single step supercritical carbon dioxide (SC-CO2) extraction resulted mostly in removal of neutral lipids and a part of glycolipids, but phospholipids were not extracted. Addition of ethanol to SC-CO2 increased the amount of glycolipids and phospholipids in the extract. TLC pattern of algal lipids showed that the main part of neutral lipids consisted of diglycerides, triglycerides, hydrocarbons, free sterols, and sterol esters. The glycolipids were mostly monogalactosyl diglyceride, digalactosyl diglyceride, esterified sterol glycoside, and sterol glycoside. In phospholipids, phosphatidyl choline, phosphatidyl glycerol, and phosphatidyl ethanolamine were the main compounds. Fatty acid composition patterns indicated the main fatty acids to be 16:0, 16:1, 16:2, 16:3, 16:4, 18:1, 18:2, and 18:3(a). Relatively high recovery of polyunsaturated fatty acids and essential fatty acids in supercritical fluid extracted algal lipids and proteins isolates were observed.

Lipid content and fatty acid composition of green algae Scenedesmus obliquus grown in a constant cell density apparatus.

The lipids of alga Scenedesmus obliquus grown under controlled conditions were separated and fractionated by column and thin-layer chromatography, and fatty acid composition of each lipid component was studied by gas-liquid chromatography (GLC). Total lipids were 11.17%, and neutral lipid, glycolipid and phospholipid fractions were 7.24%, 2.45% and 1.48% on a dry weight basis, respectively. The major neutral lipids were diglycerides, triglycerides, free sterols, hydrocarbons and sterol esters. The glycolipids were: monogalactosyl diglyceride, digalactosyl diglyceride, esterified sterol glycoside, and sterol glycoside. The phospholipids included: phosphatidyl choline, phosphatidyl glycerol and phosphatidyl ethanolamine. Fourteen fatty acids were identified in the four lipid fractions by GLC. The main fatty acids were C18:2, C16:0, C18:3(alpha), C18:1, C16:3, C16:1, and C16:4. Total unsaturated fatty acid and essential fatty acid compositions of the total algal lipids were 80% and 38%, respectively.

Effect of processing and storage on protein and lipid composition of peas

Changes in protein and lipid contents of peas ( P. sativum L.) at various stages of processing and storage at different temperatures over a six-month period were studied. Blanching had very little effect on protein or protein amino acids of peas while free amino acids were greatly affected. Immediately after bottling and canning peas, total protein differed little from that of blanched, unpackaged peas. However, free amino acids decreased much more than did protein amino acids. Storage of canned peas for six months at room temperature caused changes in some protein amino acids. Total lipids of fresh peas did not change after blanching, bottling or canning. After storage for six months, no changes were observed in the total lipids while there were increases in glycolipids and decreases in phosphatides. Increases in monogalactosyl diglycerides and decreases in digalactosyl diglycerides were also observed.

Lipid Composition of Garlic

AbstractNeutral, glyco‐ and phospholipids of garlic were resolved into their component fractions by thin layer chromatography. Neutral lipids contained considerable quantities of monoglycerides (18.5%), diglycerides (14.2%), sterols (16.3%) and triglycerides (41.5%) respectively. The phospholipid fraction was rich in phosphatidyl choline (23.5%), phosphatidyl ethanolamine (17.9%), lysophosphatidyl choline (11.8%) and lysophosphatidyl ethanolamine (8.2%). Digalactosyl diglyceride (10.1%), sterol glycoside (15.6%), cerebrosides (8.1%), acylsterol glycoside (38.6%) and monogalactosyl diglyceride (22.5%) were the major components of the glycolipids of garlic. Lauric, myristic, palmitic and linoleic acids constituted the major fatty acids of monoglycerides, diglycerides and free fatty acid fractions whereas palmitic, linoleic and linolenic acids were the major fatty acids of triglycerides. Palmitic and linoleic acids were the major fatty acids of garlic phospholipids. Except the acylsterol glycoside fraction glycolipids were rich in lauric, palmitic, linoleic and linolenic acids; palmitic acid was the only major fatty acid of acylsterol glycosides.

Effect of kinetin (6-furfuryl aminopurine) on changes in lipids in relation to growth of excised cotyledons of squashmelon ( Citrullus vulgaris var. Fistulosus)

Kinetin (6-furfuryl aminopurine) at 20 ppm resulted in the maximum increase in the size and the fresh weight of isolated cotyledons of squashmelon. The content of free fatty acids remained constant both in treated and control cotyledons. There was an increase in the total phospholipids, glycolipids, digalactosyl diglycerides and carotenoids. The content of reducing sugars increased significantly and that of sucrose reduced drastically with kinetin treatment.

Effect of Frost Hardening on Lipid and Fatty Acid Composition of Chloroplast Thylakoid Membranes in Two Wheat Varieties of Contrasting Hardiness

Lipid and fatty acid composition of chloroplast thylakoid membranes was determined in two varieties of wheat (Triticum aestivum L.), the hardy Miranovskaja and the sensitive Penjamo. Plants were grown at room temperature or under frost hardening conditions (1.5 degrees C). Changes in lipid and fatty acid composition of the isolated thylakoids could be related to the temperature dependence of light-stimulated proton uptake. Changes in the thylakoid phospholipids upon hardening of the two varieties did not show any direct relation with low temperature tolerance of light-dependent H(+) uptake; neither did changes in phospholipid fatty acid chain lengthening to 20 and 22 C-atoms in combination with increased desaturation up to 6 double bonds. Increased low temperature tolerance of light-induced H(+) uptake by hardening was correlated with the following glycolipid changes: maintained glycolipid level, a proportionally increased digalactosyl diglyceride fraction, a decrease in thylakoid monogalactosyl diglyceride, increased sulfolipid fatty acid chain lengthening (20 and 22 C-atoms), and increased sulfolipid desaturation (4-6 double bonds). We suggest that the above mentioned changes in glycolipids have adaptive value for low temperature tolerance of light-dependent proton uptake.

Controlled deposition of lipid monolayers and bilayers onto mica and direct force measurements between galactolipid bilayers in aqueous solutions

A description is given of the Langmuir-Blodgett deposition technique with which lipid monolayers or bilayers are deposited onto molecularly smooth mica surfaces. Results are given for the deposition of the phospholipids dipalmitoyl phosphatidylethanolamine (DPPE), dilauroyl phosphatidylcholine (DLPC), dimyristoyl phosphatidylcholine (DMPC), dipalmitoyl phosphatidylcholine (DPPC), and the galactolipids monogalactosyl diglyceride (MGDG) and digalactosyl diglyceride (DGDG). Mica covered with a deposited hydrophobic monolayer of DPPE is particularly suitable as a substrate for deposition of a second layer of a desired lipid to form a bilayer. With the help of the measured monolayer compression isotherms, the deposition of this second layer is carried out such that the deposited headgroup area of lipids in the second layer can be controlled accurately. After bilayers are deposited onto mica surfaces, the direct force measurement technique of Israelachvili is applied to measure surface interactions between two opposing bilayers. Results are given for the interactions between galactolipid bilayers. The experimental data show that doubling the number of sugar units on the bilayer surface doubles the distance range of the short-range repulsive hydration force. Below 4 nm, the distance dependence of the long-range Van der Waals interaction between DGDG bilayers in aqueous solutions obeys the nonretarded Hamaker equation. The experimental Hamaker constant in pure water is found to be 7.5 ± 1.0 × 10 −21 J which decreases to a value 3.1 ± 0.6 × 10 −21 J upon addition of 0.2 M NaCl, in accordance with the expected screening of the temperature-dependent contribution to the Van der Waals interaction.